Refrigeration



March 1967 L H. LEONARD, JR 3,3@9,9$

REFRIGERATION Filed Jan. 4, 1965 4 Shgets-Sheec 1 INVENTOR. LOUIS H. LEONARD, JR.

ATTORNEY.

March 21, 1967 L. H. LEONARD, JR

REFRIGERATION 4 Sheets-Sheet 2 Filed Jan. 4, 1965 FIG. 3

INVENTOR.

LOUIS H. LEQNARD,JR. MFM

ATTORNEY.

March 21, 1967 1.. H. LEONARD, JR 3,399,896

REFRIGERATION Filed Jan. 4, 1965 4 Sheets-Sheet 5 INVENTOR LOUIS H. LEONARD, JR.

WMM

ATTORNEY.

March 21, 1967 Filed Jan. 4, 1965 L. H. LEONARD, JR

REFRIGERATION 4 Sheets-Sheet 4 JNVENTOR. LOUIS H. LEONARD JR.

W/Mf/W ATTORNEY.

United States Patent 3,309,896 REFRIGERATION V Louis H. Leonard, Jr., Dewitt, N.Y., assignor to Carrier Corporation, Syracuse, N.Y., a corporation of Delaware Filed Jan. 4, 1965, Ser. No. 423,072 12 Claims. (Cl. 62-477) This invention relates to cooling and heating and, more particularly, to an absorption refrigeration machine and method for providing cooling or heating.

It is a primary object of this invention to provide a new and improved refrigeration machine and method for providing refrigeration. More particularly, it is an object of this invention to provide such a machine and method which may be operated for heating or cooling a load.

An important object is to provide a new and improved refrigeration machine and method of providing refrigeration wherein fiuids flow by gravity between refrigeration components of the machine in lieu of pumping the fluids between the components. A related object is plOVlSlOII of such a machine and method wherein the components are rotated in one direction to provide cooling and in an opposite direction to provide heating.

Another object is provision of a new and improved absorption refrigeration machine including a thermal msulating barrier defining a heat rejection and refrigeration side and an opposite heat input side, with an absorber and evaporator on the heat rejection and refrigeration side and a generator on the heat input side, these components communicating with each other and being mounted for rotation with the barrier for the passage of refrigerant and absorbent solution between the components to provide heating or cooling for a load depending on the direction of rotation. A related object is provision for storing heat from fluids passing from the generator to cool these fluids and liberating the stored heat to fluids passing to the generator to heat the fluids.

Still another object is provision in an absorption refrigeration machine having an absorber, evaporator and a generator, mounted for rotation about a generally horizontal axis, of a method of providing refrigeration comprising rotating the assembly about the aids and heating the generator when it is below the absorber and evaporator so that the refrigerant boils out of the solution in the heated generator and rises to the evaporator and the strong hot absorbent solution flows into the absorber as the generator is rotated above the absorber, the weak solution flowing from the absorber into the generator as the absorber is rotated above the generator. A related object is provision of the additional step of storing heat from the fluids passing from the generator and liberating the stored heat to the fluids passing to the generator.

These and other objects of the invention will be apparent from the following description and the drawings in which:

FIGURE 1 is a schematic sectional side view taken generally along the line I--I in FIGURE 2 and illustrating a rotating absorption refrigeration machine;

FIGURE 2 is a fragmentary vertical sectional view taken generally along the line II-II in FIGURE 1;

FIGURE 3 is a schematic sectional side view taken generally along the line III-III in FIGURE 4 and illustrating a preferred embodiment of the invention;

FIGURE 4 is a vertical sectional view taken generally along the line IVIV in FIGURE 3, with parts broken away and removed to more clearly illustrate the invention during cooling operation;

FIGURE 5 is a view similar to FIGURE 4 but illustrating the apparatus during heating cycle operation; and

FIGURE 6 is a modification of the apparatus shown in FIGURES 1 and 2 and applicable as well to the modification shown in FIGURES 3-5.

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With reference to FIGURES 1 and 2, an absorption refrigeration machine for providing heating or cooling includes a housing 11 in which is mounted a heat insulating barrier 12 extending vertically through generally the center of the housing 11 and including a center disc portion 13. The disc 13 is mounted on a generally horizontal shaft 14 suitably journalled in the housing 11 and connected with a motor 15 mounted on the housing for rotating the shaft 14 and the disc. An assembly or unit of absorption refrigeration components 16 is preferably metal and fully hermetic, that is, liquid and gas tight, and is mounted on the disc 13 for rotation therewith. The unit 16 includes a hollow spherical absorber 17 and radialiy outwardly thereof a hollow spherical evaporator 18 both on a heat rejection and refrigeration side 19 of the barrier 12 within the housing 11. A radial neck 20 extends from the evaporator 18 into the absorber 17 for retaining liquid within the absorber during certain portions of rotation of the assembly. A hollow spherical generator 21 is on an opposite or heat input side 22 of the barrier 12 and is in fluid communication with the absorber 17 through a solution heat exchanger 23 in the form of a tube 24 containing a heat storing filler 25 such as loosely packed metal turnings, coarse steel wool or similar substance with a large surface contact area. The tube 24 is preferably covered with a suitable insulation 26. The tube 24 is directly mounted on and extends through the center of the disc 13 and has one end which defines a neck 26a extending into the absorber 17 and a bafl'le 26b in the neck to retain solution in the absorber and tube, respectively, during portions of the cycle as described later. The heat exchanger 23 receives and stores heat from hot fluid passing from the heated generator 21 and liberates the stored heat to fluid passing to the generator to preheat this fluid. A drain tube 27a (FIGURE 2) passes weak absorbent solution trapped by the neck 26a in the absorber, to the heat exchanger 23 as the absorber is rotated upwardly in a ciockwise direction. A storage chamber and subcooler 2-8 in the form of a hollow-sphere is along side and generally intermediate the absorber 17 and evaporator 18 and is connected therewith by means of opposed tubes 36 and 31.

For maximum performance, the cycle preferably uses a solution of lithium nitrate and ammonia as the absorbent and pure ammonia as the refrigerant thus eliminating the need for analyzers and rectifiers as required in conventional aqua-ammonia systems. Alternatively, refrigerant R22 and absorbent dirnethylether of tetraethylene glycol or other suitable combinations which are stable and noncorrosive in the absence of water may be used. Keeping water out of a completely hermetic, metal, high pressure system of the present type is no problem.

During cooling operation, the disc 13 and the refrigeration unit 15 are rotated at five to ten revolutions per hour in a clockwise direction as indicated by the arrow 32 in FIGURE 2. As the generator 21 is rotated through the lower portion of its orbit (dashed line in FIGURE 1) and the absorber 17 and evaporator 18 move through the upper portions of their orbits, the weak solution resulting in the absorber 17 from passage of refrigerant vapor from the evaporator 18 into the absorbent solution, flows through the drain tube 27a and the heat exchanger 23, and heat is liberated to the weak solution thus preheating the solution as it enters the generator 21. At the lower portion of the generator orbit, heat is applied as by a burner 33 mounted in the housing 11, thus causing the refrigerant to evaporate from the weak solution, which is being reconcentrated, and rise through the filler 24 in the solution heat exchanger 23 in which it is desuperheated and the heat stored in the heat exchanger filler. Then, the refrigerant vapor passes through the absorber 17 and into the evaporator 18 which is in a position above the generally horizontal axis of rotation of the shaft 14. Upon continued rotation of the generator 21 upwardly above the axis of rotation, the reconcentrated now strong hot solution fiows through the solution heat exchanger 23 and is temporarily retained therein by the bafiie 26b (FIGURE 1) as it rejects the heat to the filler 25 wit-h the heat stored in the filler. Upon continued rotation, the reconcentrated strong solution flows over the baffle 26b and into the absorber 17 and is retained therein and prevented from fiowing into the evaporator 18 by the neck 29 which projects within the absorber, as is more fully described later. If desired, the burner 33 for heating the generator 21 can be rigidly attached to the disc 13 and supplied with fuel such as gas through an on-otf valve (not shown) and a suitable connection at the center of the rotating barrier 12.

The absorber 17, evaporator 18 and storage chamber 28 serve as a condenser when in the upper portions of their orbits to condense the refrigerant vapor. Suitable means, such as a fan 34, may be provided in the housing 11 for aiding the condensing function. As the evaporator 13 moves to the lower portion of its orbit it enters a trough 35 of water 36 or other suitable heat exchange medium, and as the refrigerant vapor, created by absorption of heat from the water, is absorbed by the absorbent, the water is cooled and may be passed to suitable heat exchangers (not shown) for cooling a load. Alternatively, suitable ice forming means, such as suitable pockets 37 on the exterior of the evaporator 18 may be utilized for forming ice which is released from the evaporator as it moves upwardly and is exposed to warm ambient air or as the evaporator receives the hot refrigerant vapor from the generator and condenses the refrigerant. A suitable chute 38, such as is shown in FIGURE 2, may be provided for collecting and conveying the resultant ice away from the machine. During this portion of the cycle, any residual absorbent solution in the evaporator 18 passes through a solution return pipe 39 into the absorber. The solution trapped in the absorber 17 by the neck 25a flows through the drain 27a into the heat exchanger 16 and the generator 21.

During heating operation, the disc 13 is rotated counterclockwise and with the fan 34 off, the water in the trough 35 is heated, as described later.

Mixing fins, as 49, located in the bottom of the absorber 17 (when it is in the lower portion of its orbit), constantly mix the absorbent solution as it flows over the fins to provide eflicient absorption process. The pressure conditions within the refrigeration components may change several hundred pounds during the transition from freezing cycle to reconcentration process, but at any time there is but a very slight pressure difference between any of the components as 17, 18, on the one hand and 21, on the other hand.

Accidental overconcentration and solidification can be easily prevented by properly charging the refrigerant and absorbent combination and proper sizing of means as 27a, 28 and 39 between the evaporator 18 and absorber 17. In other words, with the evaporator 18 and absorber 17 at the upper portions of their orbits, if the heat from the burner 33 is left on too long, the excess refrigerant condensed out would simply drain back into the generator 21 through. the solution heat exchanger 23 and again be boiled out, so that the machine is virtually solidification proof.

With reference to the preferred embodiment of FIG- URES 35, a plurality of refrigeration units 41, in lieu of the unit 16 in FIGURES l and 2, are mounted on a rotating disc 42 of a heat insulating barrier 43 within a housing 44, generally as previously described.

The units 41 are concentric about and spaced on the disc from an axis of rotation defined by a shaft 45 journalled in the housing 44 and driven by a motor 46 on the housing. The units 41 diverge outwardly from their clustered generators 47 on a heat input side 48 of the barrier within a small heating chamber 49. The chamber 49 is heated in any suitable manner as by a burner 50. The generator 47 and a solution heat exchanger 5% of each unit 41 are in the form of a hollow generally conical member 51 with the generator 47 at the apex and having an open base end defining a neck 51a extending into a hollow spherical absorber shell 52 and a baffle 51b in the neck 51a to retain absorbent in the absorber and heat exchanger, respectively, as previously described with reference to FIGURES 1 and 2, and as illustrated in FIGURES 35. A neck 53 extends from an evaporator 54 into the absorber 52, all as described and oriented with reference to the embodiments of FIGURES 1 and 2. Similarly, a storage vessel and subcooler chamber 55 is connected by tubes 56 and 57 between the evaporator 54 and absorber 52 as previously described.

As shown in FIGURE 6, the solution heat exchangers 23 or 50 may be in the form of a heat exchanger 58 which includes a chamber 59 sealed about a tube 59a of steel wool filler or the like. The chamber 59 contains a liquid 5% which vaporizes upon absorbing heat at the temperature of the hot solution, and if desired, the outside of the chamber 59 may be insulated.

Upon rotation of the disc 42 in a clockwise direction as indicated by the arrow in FIGURE 4, the absorption cycle progresses as previously described. More particularly, eight refrigeration units 41 are illustrated in the embodiment of FIGURES 35, a portion of these units being removed in FIGURE 3 for clearer illustration. For purposes of description, the positions of the units illustrated in FIGURES 4 and 5 have been lettered A through H in a clockwise direction beginning at the upper portion of the figures. During cooling cycle operation, illustrated in FIGURE 4, as far as any unit disposed in position A is concerned, all solution has returned through the solution heat exchanger 50' to the generator 47 which is being heated at the bottom of its unit 41 to drive off refrigerant vapor. In position B, the generator 47 is still being heated by the burner 50 and the solution is reconcentrated with refrigerant vapor passing to the absorber 52 and evaporator 54 and being condensed as it engages the relatively cooled inside surfaces of the absorber and evaporator and drains down these surfaces and through tube 57 and 55, respectively, into the subcoolei and storage chamber 55 (position C) for subsequent passage to the evaporator 54 through tube 56 (position). The evaporator 54, absorber 52., and the storage chamber and subcooler 55 serve as a condenser in addition to their respective normal functions. In position C, the reconstituted absorbent solution, considered strong solution because of its ability to absorb refrigerant, is held in the heat exchanger by the bafile 51b and cooled by the filler. In position D the solution flows over the baffle and into the absorber 52 where it collects and is retained therein by the neck 53 as it is subcooled and the previously condensed refrigerant drains to the evaporator 54. In position E, the evaporator 54 is in a water tank 590 in the housing 44, either cooling chilled water oil therein for passage to a load having a cooling requirement, or freezing ice cubes in pockets 'as previously described. Solution in the absorber is preferably mixed by fins, as 61a, as previously described. In passing through position E, refrigerant vapor created by the heat transfer between the water 63 and the refrigerant is absorbed by the absorbent solution, rendering the solution weak, that is, reia tively incapable of absorbing more refrigerant vapor. As the unit rotates to position F any residual solution in evaporator 54 will start flowing through a solution return pipe 611; to the absorber. Weak solution starts to return from the absorber through a drain 61c to the generator 47 and passes through the hot solution heat exchanger 50 whereupon refri erant vapor begins to be released and harvests ice cubes, if any, formed in the evaporator pockets (not shown), whereupon the ice cubes drop into a chute (not shown), as previously described. The solution continues to return to the generator 47 in position H 'as the unit 41 rotates upwardly back to the starting position A. It should be noted that any residual absorbent solution in the evaporator has been returned to the generator through the pipe 61!). A fan 62 (FIGURE 3) may be employed to improve condensing.

For winter heating operation the direction of rotation of the disc 42 and the units 41 is reversed to a counterclockwise direction as indicated by the arrow in FIGURE 5. The fan 62 (FIGURE 3) or other cooling means for the condensing function is rendered inoperative. As a unit 41 moves from position A to position G, hot gaseous refrigerant and hot strong solution pass from the generator 47 into the absorber 52 and into the evaporator 54 through the solution return pipe 61b (comparable to the pipe 39 in the modification of FIG- URES 1 and 2) connecting the absorber 52 and evaporator 54 on a side of the assembly opposite the storage chamber and subcooler 55. Continued counterclockwise rotation from position G through the water trough 59c heats the water 69 which is suitably passed to a load having a heating requirement. Subsequent rotation from the water trough 59c upwardly back to position A returns the condensed refrigerant and solution to the generator 47, as indicated in FIGURE 5, whereupon the cycle is repeated.

Both heating and cooling capacity can be varied from full to zero load by simply modulating the fuel to the burner 33 or 53 to vary the heat input to the generator 21 or generator 47. The heat input may be modulated responsive to leaving chilled or hot Water temperature in the trough 35 or 590. Provision of a modulating type control system rather than the conventional on-oii' control usually provided on absorption machines results in much lower operating costs. The system may be operatecl to provide free cooling with low condensing temperatures by retaining the evaporator in the trough of water so that as the refrigerant vaporizes in the evaporator it is condensed in the absorber and overflows back to the evaporator, thus requiring no energy input for off-season cooling. For increased heating capacity the entire heat rejection side of the machine may be sprayed with water passed to the load. It should be noted that machine size or capacity variation can easily be accomplished be either adding or taking away the number of individual units 41. Similarly, a machine may incorporate more than one rotating disc, as 13 or 42, and associated units, as 16 or 41. The machine may be so constructed that rotation is provided by the flow of water in the trough 35 or 59c engaging the individual units, and the assembly may be rotated in a start-stop fashion as by incorporating a double rachet device similar to those used on spring wound pendulum clocks thus providing additional agitation in the absorber 17 or 52 and evaporator 18 or 54 to substantially improve overall heat transfer.

The machine is suited for use not only as a heat operated air conditioning machine or an ice cube maker but also as a water chilling machine, an automotive air conditioner, a saline water converter, a portable camping ice cube maker or refrigerator, a direct expansion air conditioner, a low temperature brine chiller, plus many other variations.

The disc 42 rotates slowly at five to ten revolutions per hour and the rotation of the units eliminates need for solution or refrigerant pumps or other transfer devices which are very impractical or expensive in cycles of this type, which sometimes encounter pressure differences between the high and low portions of the cycle of several hundred pounds. It should be noted that each unit of the present machine operates at a relatively constant pressure throughout on either the refrigerant or regeneration cycle so that large pressure differences never exist in any given unit, although the pressure variation in different portions of the cycle may vary substantially. The machine contains a generator on the heat input side of the system that acts only as a generator under all conditions and is always kept warm and is not cooled down during operation. During the regeneration process, the storage vessel, evaporator and absorber act as air-cooled refrigerant condensers which automatically and simply harvest ice cubes in the event the machine is used as an ice maker.

It is preferable that the metal mass of the evaporator, as 18 or 54, be kept to a minimum to maintain good cycle eificiency. This is the only portion of the entire system that undergoes a substantial temperature change during operation. The solution heat exchanger greatly increases the efiiciency of the system and the filler material such as steel wool should have a heat absorbing capacity slightly in excess in the amount of heat liberated by the strong, reconcentrated solution as it flows from the generator to the absorber. It should also have enough heat absorbing capacity to store the heat liberated by the regenerated refrigerant vapor in passing from the generator to the condensers during the reconcentration cycle, and as illustrated in FIGURES 1 and 2, should be well externally insulated.

To summarize the operation of the system, with the entire charge of absorbent solution in the generator, as 21 or 47, as heat is applied, hot superheated refrigerant vapor passes through the heat absorbing material in the solution heat exchanger, as 23 or 50', on its way to the refrigerant condensing portion including the absorber, as 17 or 52, evaporator, as 18 or 54, and storage chamber, as 28 or 55. As the vapor passes through the heat exchanger it is cooled, the heat being stored in the metal fill. As the generator is gradually rotated into a position where it can drain, the hot concentrated solution trickles through the metal packing, gradually cools, and the heat is stored in the fill ready for the next phase of the cycle. When the assembly is rotated to the position where the solution is returned from the absorber to the generator, the cold weak solution is gradually preheated by a hot fill as it flows to the generator. The metal packing in the heat exchanger also doubles as an eliminator section for the generator, allowing for much faster regeneration without the danger of solution carryover.

While a preferred embodiment of the invention has been described and illustrated, it will be understood the invention is not limted thereto but may be otherwise erbodied within the scope of the following claims,

I claim:

1. In an absorption refrigeration machine, the combination of an absorber for holding absorbent solution, an evaporator communicating with said absorber .for holding refrigerant and for the passage of refrigerant into said absorber, a generator separate from said absorber for reconcentrating weak solution directed thereto from said absorber, means providing communication between said absorber and said generator for the passage of the refrigerant and solution therebetween, means for selectively positioning said generator above and below said absorber and evaporator for the flow of refrigerant and solution between the generator and the absorber and evaporator, and means for heating said generator when the generator is at a lower elevation than said absorber.

2. In the machine of claim 1, said absorber being above said evaporator when said generator is above said absorber and evaporator, and means for retaining absorbent liquid in said absorber when the absorber is moved to a position above said evaporator.

3. In an absorption refrigeration machine, the combination of a refrigerantion unit including an absorber for holding absorbent solution and an evaporator generally radially outwardly of and communicating with said absorber for holding refrigerant and for the passage of refrigerant vapor into the solution in said absorber, a generator separate from said absorber for reconcentrating weak solution from said absorber when the generator is below said absorber and evaporator, and solution heat exchanger means providing communication between said absorber and said generator for the passage of the refrigerant and solution therebetween and for storing heat from strong hot solution passing from said generator to said absorber and releasing the stored heat to Weak solution passing from said absorber to said generator, means for rotating said unit, and means for heating said generator when the generator is at a lower elevation than said absorber.

4. In an absorption refrigeration machine, the combination of a housing, a thermal insulating barrier in said housing mounted for rotation about a generally horizontal axis, a heat rejection and refrigeration side on one side of the barrier and a heat input side on a opposite side of said barrier, a refrigeration unit mounted on said barrier for rotation therewith and including on said one side an absorber for holding absorbent solution and an evaporator generally radially outwardly of and communicating with said absorber for holding refrigerant and for the passage of refrigerant vapor into the solution in said absorber when the absorber is above the evaporator, a generator on said opposite side for reconcentrating weak solution from said absorber when the generator is below said absorber and evaporator, and solution heat exchanger means providing communication between said absorber and said generator for the passage of the refrigerant and solution therebetween and for storing heat from hot fluid passing from said generator to said absorber and evaporator and releasing the stored heat to weak solution passing from said absorber to said generator, means for rotating said barrier and unit in one direction to provide cooling, and means on said opposite side of said barrier for heating said generator when the generator is at a lower elevation than said absorber.

5. The machine of claim 4 including means for storing the refrigerant and for passing the refrigerant between said evaporator and absorber.

6. The machine of claim 5, said means for storing the refrigerant passing said refrigerant from said absorber to said evaporator, and means for retaining said absorbent in said heat exchanger means until said means for storing said refrigerant is in position for effectively preventing the passage of absorbent into said evaporator.

7. The machine of claim 4, and means for rotating said barrier and unit in a direction opposite said one direction to provide heating rather than cooling.

8. The machine of claim 4, and means for containing water and receiving said evaporator as said evaporator is rotated below said axis to cool the water.

9. The machine of claim 8, and means on the evaporator for forming and holding ice as said evaporator is rotated in said one direction through said means for containing water, and for releasing said ice as said evaporator is heated upon being rotated in said one direction above said generator.

16. The machine of claim 4 including cooling means operable for cooling said evaporator and absorber as said evaporator and absorber are rotated in said one direction generally above said generator to condense said refrigerant and cool said solution, and said cooling means being effectively inoperable when said assembly is rotated in a direction opposite said one direction, to provide heating rather than cooling.

11. In an absorption refrigeration machine the combination of a housing, a thermal insulating barrier in said housing mounted for rotation about a generally horizontal axis, a heat rejection and refrigeration side on one side of the barrier and a heat input side on an opposite side of said barrier, a refrigeration unit mounted on said barrier for rotation therewith and including, on said one side, an absorber for holding absorbent solution and an evaporator generally radially outwardly of said absorber for holding refrigerant, means for the passage of refrigerant vapor into said absorber, means for effectively preventing the passage of absorbent solution from said absorber into said evaporator when said evaporator is below said absorber, means for the passage of residual absorbent solution from said evaporator to said absorber as said evaporator and absorber move to a position above said generator, a generator on said opposite side of said barrier for reconcentrating weak solution from said absorber when the generator is below said absorber and evaporator, and solution heat exchanger means providing communication between said absorber and said generator for the passage of the refrigerant vapor and solution therebetween and for storing heat from strong hot solution and refrigerant vapor passing from said generator to said absorber and releasing the stored heat to weak solution passing from said absorber to said generator, means for the passage of solution from said absorber to said heat exchanger as said absorber moves above said generator, means for retaining refrigerant condensate in said absorber, means for the passage of said condensed refrigerant from said absorber to said evaporator and for subcooling the refrigerant condensate, means for effectively preventing the passage of said strong soiution from said heat exchanger to said absorber before said refrigerant has passed through the last said means from said absorber to said evaporator, means for rotating said barrier and unit in one direction to provide cooling and in an opposite direction to provide heating, and means on said opposite side of said barrier for heating said generator when the generator is at a lower elevation than said absorber.

12. In a method of operation of an absorption refrigeration machine having an assembly including an absorber, evaporator and generator separate from said absorber with these components in suitable communication for the passage of refrigerant and absorbent therebetween, the steps which consist in heating the generator when it is below the absorber and evaporator to reconcentrate weak solution with the resultant refrigerant vapor rising from the generator to the evaporator, positioning said generator above said absorber for gravity flow of strong solution from said generator into said absorber, positioning the absorber above the generator for gravity flow of weak solution from the absorber to the generator to be reconcentrated in the generator and storing heat from fluids passing from said generator and liberating the stored heat to fluids passing to said generator.

References Cited by the Examiner UNITED STATES PATENTS 1,821,509 9/1931 Gay 62-482 X FOREIGN PATENTS 518,005 2/1931 Germany. 553,293 6/1932 Germany. 559,075 9/1932 Germany. 204,602 8/ 1939 Switzerland.

LLOYD L. KING, Primary Examiner 

1. IN AN ABSORPTION REFRIGERATION MACHINE, THE COMBINATION OF AN ABSORBER FOR HOLDING ABSORBENT SOLUTION, AN EVAPORATOR COMMUNICATING WITH SAID ABSORBER FOR HOLDING REFRIGERANT AND FOR THE PASSAGE OF REFRIGERANT INTO SAID ABSORBER, A GENERATOR SEPARATE FROM SAID ABSORBER FOR RECONCENTRATING WEAK SOLUTION DIRECTED THERETO FROM SAID ABSORBER, MEANS PROVIDING COMMUNICATION BETWEEN SAID ABSORBER AND SAID GENERATOR FOR THE PASSAGE OF THE REFRIGERANT AND SOLUTION THEREBETWEEN, MEANS FOR SELECTIVELY POSITIONING SAID GENERATOR ABOVE AND BELOW SAID ABSORBER AND EVAPORATOR FOR THE FLOW OF REFRIGERANT AND SOLUTION BETWEEN THE GENERATOR AND THE ABSORBER AND EVAPORATOR, AND MEANS FOR HEATING SAID GENERATOR WHEN THE GENERATOR IS AT A LOWER ELEVATION THAN SAID ABSORBER. 